“I’m really lucky, as not every mum is as fortunate as I am to be able to move things around like that,” she says. “I’m naturally busy and like fitting lots of things in. It keeps me out of trouble!”

Later on, after a long day in front of the camera, she’s got several hours of rehearsing her latest tracks with her band.

It’s a schedule hectic enough to send the most organised of mums into a flap – but not Sophie, whose no-drama attitude has served her well.

Take, for example, a rare date night with her hubby, The Feeling’s bassist Richard Jones, at an awards bash back in June.

It was the singer’s red-carpet comeback having given birth seven months earlier, and she excitedly Instagrammed pre-party pics of her semi-sheer yellow maxi-dress and a sparkly leotard underneath with the caption: ‘So fun to get dressed up!’

Most of us would have skulked off home with imminent diet plans, but instead Sophie publicly flagged up the incident in an inspiring Instagram post that went on to gain thousands of likes thanks to the overriding message of: “I don’t have a flat tummy. This is OK.”

“What’s sweet is that I had quite a few comments from my girl friends saying that it had also happened to them. I’m the same as anyone else – I look at other people and think: ‘God, they seem to have so easily moved on to the next bit.’”

“When you have a baby, your body’s priority is not getting you back into your old clothes – it’s feeding your baby or repairing,” she says. “Having had four pregnancies, I know you have to trust it and the process it goes through. It will get you back there, but it doesn’t happen overnight. I think that’s why I was quite relaxed about it – I’ve seen it happen before, and even if I was juicing everything in sight it would still take a while."

It’s a refreshing change in a world of celebrities who seem to ping back into shape in a matter of weeks then flaunt it in sexy online selfies.

But Sophie’s not about to pretend the transformation is an easy one.

“It’s a bit taboo,” she says. “I’d just had Jesse and people would say: ‘Oh my god, you can’t tell!’ I was like: ‘You can, and that’s OK. He’s still small, I’m still feeding him and I’m not going on the treadmill.’"

“It’s all about feeling good about yourself, so if you’re someone who feels good when you have an hour to yourself at the gym, then bloody do it!”

Almost a year after giving birth, Sophie is feeling even better about her body.

Not only is she in awe of all it has been through with pregnancy and childbirth, but she’s now firmly back in her size-10 jeans.

“I feel like I have crossed over now. I’m feeling more like me and not so much like I’ve just had a baby – it always takes me around 10 months to a year. It’s important to be completely forgiving of yourself if you are taking your time.”

After Sophie stopped breastfeeding when Jesse was six months old, she slowly but surely started eating healthily and heading to the gym three times a week for boxing and Pilates.

It certainly paid off – in the flesh, she looks incredible in Topshop skinnies and a Zara lace-sleeved top.

She excitedly pulls out pieces from the rails stuffed with 1940s-inspired designs and dives straight into the changing room to try them all on.

When she finally emerges in a pair of thigh-high lace-up boots, all eyes are firmly on her never-ending legs.

“When I’m breastfeeding, I’m hungrier than ever, even more than when I’m pregnant,” she says. “I think it’s because of all the extra energy needed to make that milk, as you’re basically taking a newborn baby to a six month old. Afterwards I didn’t diet, as I’ve never been [a dieter]. I wasn’t raised that way, and my mum [former Blue Peter presenter Janet Ellis, 61] would never allow scales in the house.

“As kids, if we moaned about our clothes being too tight, she would tell us just to eat healthily and look after ourselves. It’s all a lot more simple than sometimes we make it out to be – if you want to feel good, then exercising and eating well is probably going to be the right thing to do.”

With her combination of an easy-going attitude and model looks (those razor-sharp cheekbones could cut glass), her husband Richard is one lucky guy.
The couple met in 2002 when Sophie, then 23, was auditioning musicians for her band to promote her debut album Read My Lips.

In 2003, after just six weeks of dating, Sophie discovered she was pregnant.

But there was never any doubt in their minds as to their future together.

Their baby boy Sonny, now 12, was born two months premature in April 2004.

A year later, they wed at Palazzo Terranova in Italy, and sons Kit, Ray, four, and Jesse followed.

There was one particular quality that first drew Sophie to her other half.

“Richard was the first person I went out with who said I looked great whatever I wore,” she says.

The singer discovered she was pregnant with Sonny six weeks into dating Richard

“He never said: ‘Is that skirt not a bit short?’ or: ‘Why are you going out dressed like that?’

“He always wanted to celebrate me, and actually I think that’s when you know someone really loves you. I don’t think you can really love someone if you’re trying to keep them pinned down, as it’s not healthy.”

Richard isn’t the only one who loves Sophie’s look – her retro-inspired wardrobe has earned her style icon status and helped her forge an enduring modelling career that has seen her front high-profile campaigns for the likes of Phase Eight, Pretty Polly and PETA.

All the same, she’s not above admitting she’s made the odd fashion faux-pas over the years.

“Everything I wore when I was pregnant with Sonny was pretty terrible,” she laughs. “I couldn’t find any maternity wear that felt like me, so I just tried to adapt the clothes I already had and it looked terrible. Years later, I asked Richard how he let me leave the house like that and he told me he thought it looked funny!”

Sophie's style is flawless, but she admits she's made plenty of faux-pas

The couple’s 11-year marriage is regarded as one of the strongest in the industry, but Sophie was more used to blended families after her mum and film director dad Robin Bextor separated when she was four.

She lived in London with her mum, stepdad John Leach and their children Jackson, now 29, and Martha, 25, while visiting her dad, his second wife Polly Mockford and their kids Dulce, 19, and twins Maisy and Bertie, 18, in East Sussex.

To keep her own marriage strong, Sophie imposed a rule of spending no longer than two weeks apart from Richard, as they are both often away touring.

They also rely on the smaller things in life to keep the spark alive.

“I’m a big fan of everyday, simple things like being kind, talking about your day or asking what the other person has going on,” she says. “I think you have to involve each other in everything so that the time doesn’t go by without you noticing and enjoying the same things.

“The big romantic stuff is lovely, but I try and keep an eye on the little things as they make things tick nicely.

“Recently, we felt a bit like ships in the night as Richard was doing a lot of festivals and I was doing a lot of promotion, so one evening Richard booked a babysitter for two hours and we went for a cycle along the river, had a drink and then went home. It doesn’t need to be for long, but sometimes you need to recalibrate.”

You don’t have to look at Sophie’s famous heart “family” tattoo on the top of her arm to know her clan means the world to her.

She and Richard share parenting duties at their five-bedroom detached home in Chiswick, west London, with the help of their long-term nanny Claire and Sophie’s mum, who lives just 10 minutes away.

“It can be quite hard logistically, but I’m not someone who is fazed by dealing with stuff last minute,” she says. “At the same time, I do an awful lot of planning as I want the kids’ lives to be quite consistent.

“I did a radio show recently then came home and took over as Richard had a gig. I got on with the laundry and sorted out all the school uniforms. I think everyone benefits from a healthy dose of reality, especially when your job is a bit potty. So far, so good, but it’s definitely trickier now because their needs are quite different as they are a range of ages.

“It’s not a massive difference going from three to four kids in terms of logistics, more how people perceive it. I have crossed over into big family territory! When I said I was a mum of three, people were like: ‘Oh, right.’ Now when I say I’m a mum of four they say: ‘Oh my god!’

“Our house is chaos, but it’s happy chaos. I’ve always wanted a little community. It feels totally bizarre if, for any reason, they are all out and I’m just at home alone.”

Sophie clearly embraces the craziness.

She even plotted the writing of her sixth album Familia around the birth of Jesse, and once he was born took him to the studio while recording it.

“It’s not my first baby,” she shrugs. “And I really enjoyed bringing him along for the ride.”

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Sophie clearly embraces the craziness.

She even plotted the writing of her sixth album Familia around the birth of Jesse, and once he was born took him to the studio while recording it.

“It’s not my first baby,” she shrugs. “And I really enjoyed bringing him along for the ride.”

So what about expanding their family with baby number five?

“Everyone is like: ‘Are you done now?’ I don’t know if I’ll have any more. Having four is a lot, but on the other hand, Jesse is a really good advert for babies – he’s really smiley, sleeps through the night and is very easy-going. He’s a bit of a dream baby. If we were to talk about it and Rich was here, he would make a face. If that’s me done then I’m happy.”

In front of the camera Sophie oozes poise and self-assurance, but it was hard won.

Growing up, her confidence wavered after she was bullied for having a famous mum, with some of her spiteful school mates forming an “anti-Sophie” club.

There was also that awful comment from Robbie Williams unkindly comparing her face to a satellite dish.

But since becoming a mum herself, Sophie has finally found her inner peace.

“I suppose the kids have made me less bothered,” she shrugs. “Trying to be cool is so overrated and it’s also pretty unattainable.

“When you have got a family, that’s the most important thing, and it makes you feel more galvanized. It doesn’t really matter what people think, so long as everything is right in your home.”

And as she approaches the big 4-0, Sophie is fully embracing ageing – even though she barely looks a day older than when she shot to No.1 in 2000 with Groovejet (If This Ain’t Love).

“I’m definitely more comfortable than ever in my skin,” she says.

“I like getting older – it’s brilliant and underrated. I would never want to go back to my 20s, as my 30s are great. You feel liberated and things that seemed really important you realise are not that important any more. I don’t care at all, and I’m definitely not frightened about turning 40. I think the best thing to look good is having a youthful attitude and keeping happy.”

With that, she takes out a pen from her bag and uses it as a stirrer for her cup of tea.